The RFHunter Packs an Espressif ESP32 and Analog AD8317 to Track Down Hidden Spy Gear

Security engineer Matthew Rogers has an Espressif ESP32-powered device designed to sniff out hidden wireless cameras, bugs, and other devices: the RFHunter.

"This project is an RF [Radio-Frequency] signal scanner built using an [Espressif] ESP32, [Analog Devices] AD8317 RF detector, and various other components," Rogers explains of his creation. "It's designed to detect and measure RF signals in the environment and display the signal strength on an OLED display. It's useful to find hidden cameras, wiretapping devices, and other RF-enabled devices."

While Rogers has only now released the RFHunter to the public, the project is already in its fourth iteration — having moved to a 3D-printed handheld housing designed to be assembled by hand with no tools necessary. The Espressif ESP32 handles the user interface and interprets the input from the Analog Devices AD8317, a demodulating logarithmic amplifier that converts an incoming radio signal into a decibel-scaled output.

The output of the AD8317 is processed by the ESP32 and used to display a signal strength on the OLED display, which updates in real time — allowing the user to wander around a room and hone in on the precise location of the radio signal's source, aided by a piezoelectric buzzer for audible feedback. An internal battery, connected to a boost converter which may be engineered away in a future revision, provides enough power for "weeks or months [of use] depending on usage cycles," Rogers says.

Source code and 3D print files are available on GitHub under the reciprocal GNU General Public License 3. More information on the project is available on Rogers' blog.